Spread of Avian Influenza Viruses by Common Teal (Anas crecca) in Europe

Since the recent spread of highly pathogenic (HP) H5N1 subtypes, avian influenza virus (AIV) dispersal has become an increasing focus of research. As for any other bird-borne pathogen, dispersal of these viruses is related to local and migratory movements of their hosts. In this study, we investigated potential AIV spread by Common Teal (Anas crecca) from the Camargue area, in the South of France, across Europe. Based on bird-ring recoveries, local duck population sizes and prevalence of infection with these viruses, we built an individual-based spatially explicit model describing bird movements, both locally (between wintering areas) and at the flyway scale. We investigated the effects of viral excretion duration and inactivation rate in water by simulating AIV spread with varying values for these two parameters. The results indicate that an efficient AIV dispersal in space is possible only for excretion durations longer than 7 days. Virus inactivation rate in the environment appears as a key parameter in the model because it allows local persistence of AIV over several months, the interval between two migratory periods. Virus persistence in water thus represents an important component of contamination risk as ducks migrate along their flyway. Based on the present modelling exercise, we also argue that HP H5N1 AIV is unlikely to be efficiently spread by Common Teal dispersal only

Study of influenza A virus in wild boars living in a major duck wintering site

International audienceWild birds, which are reservoirs of influenza viruses, are believed to be the original source of new influenza viruses-including highly pathogenic ones-that can be transmitted to domestic animals as well as humans and represent a potential epizootic and/or pandemic threat. Despite increasing knowledge on influenza A virus dynamics in wild birds, the viral circulation in wild boars remains largely unknown. This is of particular interest since pigs can be infected with both human and avian viruses; upon co-infection, they can act as a mixing vessel through reassortment, a mechanism that resulted in the emergence of the pandemic H1N1 virus in 2009. The Camargue (Southern France) appears as an ideal study area to investigate inter-species transmission of influenza A viruses from wild birds and possibly humans to wild boars. Indeed, the important local wild boar population shares wetland use with humans and the largest concentration of wintering ducks in France, that are both susceptible to infection by influenza A viruses. Additionally, wild boars occasionally prey on ducks. We conducted a virological and serological survey on wild boars in the Camargue (Southern France) between September 2009 and November 2010. No influenza A virus was detected in the collected nasal swabs (n=315) and no influenza specific antibodies were observed in the serological samples (n=20). As the study was mainly focused on viral excretion, which is limited in time, we cannot exclude that low or occasional influenza A virus circulation took place during the study period. Although, wild boars did not seem to be a key element in the dynamics of influenza A virus circulation in the Camargue, wild boar influenza A virus infections should be more widely studied to determine if the pattern observed here represents the normal situation or an exceptional one

Emerging infectious diseases: a long-term multidisciplinary study in Camargue

National audienceEmerging infectious diseases are actually of major concern worldwide. Most of them are zoonotic and their epidemiology must consequently be studied conjointly in humans and animals. We present here a long-term research program led in the Camargue. This area situated in the Rhone delta, crossroads of many birds‘ migration routes is a biodiversity hotspot. It appears vulnerable to disease emergence due to its key location and to the common use of wetlands by wild and domestic animals as well as humans. Since 2004, a health ecology program is led in the Camargue mainly focusing on Influenza A viruses. First, pathogen dynamics are studied in their wild reservoir. For example, a seasonal pattern of avian influenza A virus circulation in waterfowl was highlighted, an infection peak being generally observed in early fall, probably due to the massive arrival of young and possibly immunologically naive birds. Seasonality of avian Influenza viruses is currently studied in gulls. Second, pathogen transmission between wild and domestic birds is investigated. Interestingly, no highly pathogenic avian influenza virus was detected in wild birds of the region from 2006 to 2009 suggesting that migrating birds do not play an important role in the transmission of these viruses. On the other hand, the potential impact of domestic duck releases for shooting on avian influenza A viruses dynamics in wild waterfowl is currently studied. Finally, researches are led on pathogen exchanges between wildlife and humans. Antibio-resistant bacteria, similar to those circulating in humans in France, have been detected in gulls showing that they could be contaminated by human pathogens. This multidisciplinary program already proved that animal health, human health and ecology issues can be fruitfully linked to gain insight in the epidemiology of emerging pathogens. Besides, it highlights that long-term studies are needed to be able to face emerging health issues, rather than short-term studies limited to crisis periods that are necessarily insufficient

High influenza a virus infection rates in Mallards bred for hunting in the Camargue, South of France.

During the last decade, the role of wildlife in emerging pathogen transmission to domestic animals has often been pointed out. Conversely, far less attention has been paid to pathogen transmission from domestic animals to wildlife. Here, we focus on the case of game restocking, which implies the release of millions of animals worldwide each year. We conducted a 2-year study in the Camargue (Southern France) to investigate the influence of hand-reared Mallard releases on avian influenza virus dynamics in surrounding wildlife. We sampled Mallards (cloacal swabs) from several game duck facilities in 2009 and 2010 before their release. A very high (99%) infection rate caused by an H10N7 strain was detected in the game bird facility we sampled in 2009. We did not detect this strain in shot ducks we sampled, neither during the 2008/2009 nor the 2009/2010 hunting seasons. In 2010 infection rates ranged from 0 to 24% in hand-reared ducks. The 2009 H10N7 strain was fully sequenced. It results from multiple reassortment events between Eurasian low pathogenic strains. Interestingly, H10N7 strains had previously caused human infections in Egypt and Australia. The H10 and N7 segments we sequenced were clearly distinct from the Australian ones but they belonged to the same large cluster as the Egyptian ones. We did not observe any mutation linked to increased virulence, transmission to mammals, or antiviral resistance in the H10N7 strain we identified. Our results indicate that the potential role of hand-reared Mallards in influenza virus epizootics must be taken into account given the likely risk of viral exchange between game bird facilities and wild habitats, owing to duck rearing conditions. Measures implemented to limit transmission from wildlife to domestic animals as well as measures to control transmission from domestic animals to wild ones need to be equally reinforced

Emerging infectious diseases: a long-term multidisciplinary study in Camargue

National audienceEmerging infectious diseases are actually of major concern worldwide. Most of them are zoonotic and their epidemiology must consequently be studied conjointly in humans and animals. We present here a long-term research program led in the Camargue. This area situated in the Rhone delta, crossroads of many birds‘ migration routes is a biodiversity hotspot. It appears vulnerable to disease emergence due to its key location and to the common use of wetlands by wild and domestic animals as well as humans. Since 2004, a health ecology program is led in the Camargue mainly focusing on Influenza A viruses. First, pathogen dynamics are studied in their wild reservoir. For example, a seasonal pattern of avian influenza A virus circulation in waterfowl was highlighted, an infection peak being generally observed in early fall, probably due to the massive arrival of young and possibly immunologically naive birds. Seasonality of avian Influenza viruses is currently studied in gulls. Second, pathogen transmission between wild and domestic birds is investigated. Interestingly, no highly pathogenic avian influenza virus was detected in wild birds of the region from 2006 to 2009 suggesting that migrating birds do not play an important role in the transmission of these viruses. On the other hand, the potential impact of domestic duck releases for shooting on avian influenza A viruses dynamics in wild waterfowl is currently studied. Finally, researches are led on pathogen exchanges between wildlife and humans. Antibio-resistant bacteria, similar to those circulating in humans in France, have been detected in gulls showing that they could be contaminated by human pathogens. This multidisciplinary program already proved that animal health, human health and ecology issues can be fruitfully linked to gain insight in the epidemiology of emerging pathogens. Besides, it highlights that long-term studies are needed to be able to face emerging health issues, rather than short-term studies limited to crisis periods that are necessarily insufficient

Avian Influenza Circulation in the Camargue (South of France) During the 2006–07 Season

International audienceSituated at the crossroads of numerous migratory routes of Palaearctic birds, the Camargue is considered a high-risk area for the introduction and transmission of numerous avian-borne pathogens. We investigated the epidemiologic cycles of avian influenza viruses (AIVs) in the local bird community by performing regular sampling on a large variety of bird species during 11 consecutive months in 2006-07. To detect the presence of AIV, SYBR green reverse transcriptase-PCR targeting the M gene was performed on 2901 samples from 66 bird species. A clear seasonal pattern of AIV circulation in ducks was observed during autumn and winter, with higher prevalence rates in early fall. Our results also support an absence of circulation of AIV in passerine birds during spring and the wintering periods. Finally, even if the prevalence of infection was very low, AIVs were found in gulls in breeding colonies, indicating a possible specific circulation in spring in these birds

Situation of the sampling sites.

<p>Green circles represent the hunting estates where dead Mallards were sampled. Red circles represent the game bird facilities. One of the rearing estate (further named GBF3) is not represented since it is situated 50 km east from Arles, but the Mallards were sampled just before their release in several ponds of Fos–sur–Mer.</p

AIV infection rates in shot ducks.

<p>AIV infection rates in shot ducks.</p

Phylogenetic trees of H10N7 Camargue viruses.

<p>ML phylogenies reconstructed from sequences of the H10, N7, PB2 and M segments. Topological supports summarized from 100 ML bootstrap replications are shown when ≥90. H10N7 Camargue viruses are in purple. Egyptian strains are shown in orange. American viruses are in green. Asian H5N1 highly pathogenic avian influenza strains are in yellow.</p